Synthesis of a wide variety of new heterocyclic phosphorus systems will be performed. These systems will contain phosphorus in a 5-membered ring fused to cycloalkano-, azacycloalkano, and phosphacycloalkano rings. Other rings may also be present, and various substituents will be incorporated in the resulting molecules. Benzo- and cycloalkano- derivatives of 6-membered P-containing rings will also be prepared. The compounds resulting from these studies will be tested for anticancer and other biological activity. The stereochemical consequences of annelation of P-containing rings will be examined, using multinuclear nmr spectroscopy and x-ray analysis. Studies on the phosphole ring system, initiated in previous work, will be continued, with emphasis on formation of stable phospholes bearing reactive functional groups.